PDCD1 and neoplasm: The PD1/PD-L1 axis is often associated with T cell exhaustion, leading to immune evasion and tumor progression.23 Since ALK5i treatment of KPN metastases led to high PD1/PD-L1 expression but did not completely inhibit tumor growth, we hypothesized that dual inhibition of TGF-β and PD1/PD-L1 would further reduce KPN metastasis.